# ADR-021: Versioned Documents and Upgrade Path

**Status:** Proposed
**Date:** 2026-05-02
**Deciders:** Mikael Hugo

## Context

SF ships a fixed set of scaffold templates via
`src/resources/extensions/sf/agentic-docs-scaffold.ts` (the `SCAFFOLD_FILES`
array). On project bootstrap (and on every subsequent SF auto-start), the
scaffolder calls `ensureAgenticDocsScaffold(basePath)` which performs
**skip-and-create**: if a target file is missing it is written, otherwise it
is left alone.

This is correct for protecting user content but wrong for everything else:

1. **No drift signal.** When SF adds a new template (e.g. `.sf/harness/AGENTS.md`,
   `ARCHITECTURE.md`) or improves an existing one (e.g. tightens
   `RELIABILITY.md`), existing projects never notice. Only newly-bootstrapped
   projects benefit.
2. **No refresh command.** A user who hears "SF has a better template now"
   has no way to pull it.
3. **Pending content is frozen.** A file that is still the verbatim scaffold
   stub — neither the user nor any agent has touched it — is treated the same
   as a fully customized doc. SF refuses to refresh it because it cannot tell
   the two apart.
4. **Only one file is versioned.** `PREFERENCES.md` carries
   `last_synced_with_sf` in its frontmatter and gets a silent re-stamp via
   `preferences-template-upgrade.ts` on drift. Every other scaffold file is
   anonymous.

The user directive: **everything needs versioning, with upgrade paths for
documents that are not completed, perhaps with background agents.**

This ADR generalises the `preferences-template-upgrade.ts` pattern to all
scaffold-managed documents and defines a structured upgrade pipeline that can
distinguish *pending*, *editing*, and *completed* content.

## Decision

Adopt a per-document state model with explicit version markers, a
project-local manifest, drift detection, and an upgrade command. Existing
files are not stamped; they are migrated by content-hash match against an
archive of past template versions.

### 1. Document states

Every scaffold-managed file is in one of three states:

| State       | Definition | SF action on drift |
|-------------|------------|--------------------|
| `pending`   | Content equals (or hashes to) a known scaffold template version. Neither user nor agent has customised it. | Silent re-write to current template. Update marker. |
| `editing`   | Marker present and stamped, content has drifted from the stamped template. Customisation in progress. | Do not overwrite. Write `<file>.proposed` with new template + diff. Optionally dispatch background merge agent. |
| `completed` | Marker absent, OR marker explicitly says `state=completed`. | Never modified by SF. |

#### Detection

For Markdown files, the marker is an HTML comment on the **first line**:

```
<!-- sf-doc: version=2.75.2 template=RELIABILITY.md state=pending hash=sha256:abc... -->
```

Fields:

- `version` — SF semver that wrote/last-stamped the file.
- `template` — logical template id (matches an entry in `SCAFFOLD_FILES`).
- `state` — `pending` | `editing` | `completed`. Optional; default inferred
  from hash comparison.
- `hash` — sha256 of the file body **after the marker line** at stamp time.
  Used to confirm `pending` (current body still matches stamped hash) vs
  `editing` (hash mismatch ⇒ drift since stamp).

For frontmatter files (`PREFERENCES.md`), reuse the existing
`last_synced_with_sf` field and add `sf_template_state` and
`sf_template_hash`. The frontmatter path is the prior art described in
`preferences-template-upgrade.ts` — extend, do not duplicate.

State derivation:

| Marker present? | Body hash matches stamped hash? | Body hash matches some known template version? | State |
|-----------------|---------------------------------|------------------------------------------------|-------|
| yes             | yes                             | n/a                                            | `pending` |
| yes             | no                              | n/a                                            | `editing` |
| yes (`state=completed`) | n/a                     | n/a                                            | `completed` |
| no              | n/a                             | yes (legacy match via archive)                 | promote to `pending`, stamp |
| no              | n/a                             | no                                             | `completed` (untouched) |

### 2. Universal versioning — what gets versioned

Apply markers to every entry in `SCAFFOLD_FILES`. Categories:

| Category | Files (examples) | Marker mechanism |
|----------|------------------|------------------|
| Markdown docs | `AGENTS.md`, `ARCHITECTURE.md`, `docs/RELIABILITY.md`, `docs/SECURITY.md`, `docs/DESIGN.md`, `docs/QUALITY_SCORE.md`, `docs/RECORDS_KEEPER.md`, all `*/AGENTS.md` | HTML comment on line 1 |
| Frontmatter docs | `.sf/PREFERENCES.md` | Frontmatter fields: `last_synced_with_sf`, `sf_template_state`, `sf_template_hash` (extends prior art in `preferences-template-upgrade.ts`) |
| Templates / specs | `docs/design-docs/ADR-TEMPLATE.md`, `.sf/harness/specs/bootstrap.md`, `.sf/harness/AGENTS.md`, `.sf/harness/specs/AGENTS.md`, `.sf/harness/evals/AGENTS.md`, `.sf/harness/graders/AGENTS.md` | HTML comment on line 1 |
| Reference slot text files | `docs/references/*-llms.txt` | HTML comment on line 1 (Markdown comments are valid in plain text consumed by LLMs) |
| `.siftignore` and similar non-Markdown configs | `.siftignore` | Skip versioning. Sibling file `.sf/scaffold-manifest.json` records the applied version. (Rationale: hash-based legacy match is sufficient; markers in dotfiles fight tooling.) |

#### User-content files SF must never stamp

These files are user-curated by intent (per ADR-001) and **must not** appear
in `SCAFFOLD_FILES` nor be touched by the upgrade path:

- `.sf/PROJECT.md`, `.sf/DECISIONS.md`, `.sf/REQUIREMENTS.md`, `.sf/QUEUE.md`
- `.sf/milestones/**/*` (roadmaps, plans, summaries, slice artifacts)
- Any user-written exec plan, design doc, or product spec authored after
  scaffold

Verification: a unit test asserts that none of the above paths appear in
`SCAFFOLD_FILES` and that `detectScaffoldDrift` ignores them.

### 3. Scaffold manifest (`.sf/scaffold-manifest.json`)

Per-project record of what scaffold versions have been applied. Lives under
`.sf/` (gitignored runtime; per ADR-001 not durable user content).

```json
{
  "schemaVersion": 1,
  "applied": [
    {
      "path": "AGENTS.md",
      "template": "AGENTS.md",
      "version": "2.75.2",
      "appliedAt": "2026-04-30T12:00:00Z",
      "stateAtApply": "pending",
      "contentHash": "sha256:abc..."
    },
    {
      "path": "docs/RELIABILITY.md",
      "template": "docs/RELIABILITY.md",
      "version": "2.74.0",
      "appliedAt": "2026-03-12T08:11:02Z",
      "stateAtApply": "pending",
      "contentHash": "sha256:def..."
    }
  ]
}
```

Writers: `agentic-docs-scaffold.ts`, `/sf scaffold sync`,
`migrateLegacyScaffold`. Readers: `detectScaffoldDrift`, doctor check.
Failure mode: a corrupt manifest is rebuilt by re-walking files and reading
their markers — the manifest is a cache, the marker is the source of truth.

### 4. Drift detection

New module exposes:

```ts
function detectScaffoldDrift(basePath: string): ScaffoldDriftReport
```

Returns five buckets:

| Bucket | Condition | Action by `/sf scaffold sync` |
|--------|-----------|-------------------------------|
| `missing` | Template in `SCAFFOLD_FILES` but file does not exist on disk | Write the file, stamp current version |
| `upgradable` | File exists, marker present, `state=pending`, stamped version older than current SF | Silent re-write to current template, restamp |
| `editing-drift` | File exists, marker present, body hash ≠ stamped hash, **template content has changed** since stamped version | Do not overwrite. Write `<file>.proposed`. Optionally dispatch merge agent (#6). |
| `untracked` | File exists, no marker, predates this ADR | Run legacy hash match (#7). Promote to `pending` if matched, else leave alone. |
| `customized` | Marker says `state=completed`, OR marker absent and no legacy hash match | Skip. SF never modifies. |

The report is structured (one entry per file) and can be rendered as a table
for CLI output.

### 5. Upgrade paths

Per drift case:

- **missing** → write current template, stamp marker. No conflict.
- **upgradable (pending)** → silent re-render. Same pattern as
  `upgradePreferencesFileIfDrifted` in
  `preferences-template-upgrade.ts`: replace body, preserve any out-of-band
  content where the file has separable regions (frontmatter for
  `PREFERENCES.md`; for plain Markdown there is no preservation — the file
  *is* the template).
- **editing-drift** → produce `<file>.proposed` with:
  - The new template content
  - A leading `<!-- sf-proposed: ... -->` block describing source version,
    target version, and a unified diff against the **stamped template
    version**, not the current file. The agent or user can then merge
    intentionally.
  - The original `<file>` is untouched.
- **untracked** → see migration (#7). Either promote to `pending` and stamp,
  or leave fully alone.
- **customized** → never touch. Period.

### 6. Background-agent integration (stretch)

When `editing-drift` items exist and the project enables auto-merge (a new
preference flag, default off), the sync command may dispatch a
**`scaffold-keeper` background agent**. This agent:

1. Reads the stamped template version (from the `SCAFFOLD_VERSION_ARCHIVE`).
2. Reads the current template version.
3. Reads the current customised file.
4. Produces a 3-way merge: keep user customisations, apply non-conflicting
   upstream improvements.
5. Writes the result to `<file>.proposed`.
6. Posts an `approval_request` notification through the existing
   structured-notification model so the user (or a supervisor) can review
   and accept.

This ADR does not specify the agent prompt, scheduling policy, or grading
rubric. Those belong to a follow-up ADR; the architecture here merely
*enables* the integration by guaranteeing a clean three-input merge surface
(stamped version, current version, current file).

### 7. Migration strategy for existing projects

Existing projects have no markers. Migration runs once on first sync after
this ADR ships:

```ts
function migrateLegacyScaffold(basePath: string): MigrationReport
```

For each entry in `SCAFFOLD_FILES`:

1. If file does not exist → `missing`, handled by sync normally.
2. Read file, compute body sha256.
3. Look up the hash in a new constant
   `SCAFFOLD_VERSION_ARCHIVE: Record<TemplateId, Array<{ version, hash }>>`
   that records every template body shipped by every prior SF version.
4. If matched → file is verbatim from a known prior version. Promote to
   `pending`, stamp marker with `version=<matched>`, then let the normal
   `upgradable` path bring it forward.
5. If no match → user has touched it (or it predates SF tracking entirely).
   Leave the file alone, do **not** stamp. Treat as `customized`.

The archive starts empty for the version of SF that ships this ADR (no prior
versions had hashes for these templates). As SF evolves, every release that
changes a template body adds an entry mapping the previous body hash to its
SF version. Within a few releases, the archive covers the long tail of
real-world projects.

Migration is idempotent and non-destructive: the only filesystem change for
unmatched files is none.

### 8. Doctor integration

A new check in `doc-checker.ts` (or a sibling module to keep concerns
separate):

```ts
function checkScaffoldFreshness(basePath: string): DoctorFinding
```

Reports:

- Count by bucket: `missing`, `upgradable`, `editing-drift`, `untracked`.
- Severity: **warning** (non-fatal). Never blocks dispatch.
- Guidance: `Run /sf scaffold sync to refresh ${n} pending docs.`
- If `editing-drift > 0`: `Run /sf scaffold sync --include-editing to merge customised docs.`

Doctor finding integrates with the existing report rendering in
`doc-checker.ts` style — same `status`/`note` shape so consumers don't fork.

### 9. Automatic operation — primary mode

**This is the headline behaviour. Manual command operation (#10) exists only
as an escape hatch and for dry-run inspection.**

The upgrade pipeline runs automatically in three places:

1. **On every SF startup** that already calls `ensureAgenticDocsScaffold`
   (`auto-start.ts`, `guided-flow.ts`, `init-wizard.ts`). The sync runs
   synchronously in the cheap path:
   - `missing` items → write immediately (already current behaviour).
   - `upgradable` items (pending state, hash matches) → silent re-render
     immediately. No notification — no human attention needed.
   - `untracked` items → migration tries the legacy hash match in-process; if
     matched, promote to `pending` and re-render in the same pass.
   - `editing-drift` items → defer to background agent (point 3).

2. **After every milestone completion** (`auto-post-unit.ts`, `auto.ts:stopAuto`).
   The state of the codebase has just changed meaningfully — a good time to
   re-derive code-dependent docs (see "Code-as-fact verification" below).

3. **Asynchronously via the existing subagent extension** for
   `editing-drift` items and for code-as-fact re-derivation. The sync emits a
   structured notification with `kind: "approval_request"` only when the
   agent has produced a proposed change that needs review. Silent runs
   produce no notification.

The user **never has to know any of this is happening** for the common
cases. The only signal is: on a fresh `sf` invocation, the scaffold catches
up. If the agent finds something controversial, an approval-request
notification surfaces with a `<file>.proposed` artifact ready for review.

#### Code-as-fact verification

Static template refresh handles the easy case. The harder, more valuable
case: **the document has drifted not because the template changed, but
because the code has evolved past what the document claims.** Examples:

- `ARCHITECTURE.md` says the codebase has 3 modules; the code now has 6.
- `RELIABILITY.md` says exit codes are 0/1/10; the code now emits 0/1/10/11/12.
- `SECURITY.md` lists the write-gate's protected paths; the code added 2 more.

The scaffold-keeper background agent runs the **`records-keeper`** skill
(already in `src/resources/extensions/sf/skills/records-keeper/SKILL.md`)
which already specifies *"prefer source and tests for implemented behavior"*.
That skill is the agent's contract.

**Code is the fact. Documents are projections of code at a moment in time.**
When the projection drifts, the agent re-derives by reading source. When the
agent can re-derive non-controversially, it does so silently. When the change
is large enough to warrant review, it surfaces a `.proposed` artifact through
the structured notification model.

This generalises records-keeper from a skill an agent *can* run to a skill
the system runs *automatically* on a regular cadence. The records-keeper
attempt was the right idea; this ADR is what makes it autonomous.

#### Cadence

- **Synchronous on startup**: only the cheap path (hash comparisons, missing
  files, pending refreshes). Bounded by file count, runs in milliseconds.
- **Asynchronous after milestone completion**: dispatches a scaffold-keeper
  subagent. The subagent runs the records-keeper procedure on the docs whose
  source dependencies have changed since last sync.
- **Optional cron** via the existing `/loop` system: a daily background run
  for projects that don't close milestones often.

#### Failure modes are non-fatal

The pipeline is designed to fail open: any error reading a marker, computing
a hash, dispatching an agent, or writing a `.proposed` file results in the
file being left alone, a debug log line, and SF continuing normally. The
user-facing contract is "SF doesn't break my docs." Drift detection may
under-fire; it must never over-fire.

### 10. Manual command — `/sf scaffold sync` (escape hatch)

For dry-run inspection, forced refresh, and scoped operations:

```
/sf scaffold sync [--dry-run] [--include-editing] [--only=<glob>]
```

| Flag | Behaviour |
|------|-----------|
| (default) | Force the same operation that would run automatically. Useful when the user wants to refresh on demand without waiting for the next startup or milestone close. |
| `--dry-run` | Print the drift report and the planned actions. Make no filesystem changes. The primary diagnostic mode. |
| `--include-editing` | Synchronously merge `editing-drift` items inline (vs. the default async-via-subagent). Used when the user wants a definitive answer right now. |
| `--only=<glob>` | Restrict the sync to a path glob. Useful for tightly scoped refreshes (`--only=harness/**`) or for re-deriving a specific code-dependent doc (`--only=docs/RELIABILITY.md`). |

Exit code: 0 if no errors. Non-zero only if filesystem writes failed for
reasons unrelated to drift (permission, disk full).

## Implementation phases

| Phase | Scope |
|-------|-------|
| **A** | Stamp markers on all `SCAFFOLD_FILES` writes. Maintain `.sf/scaffold-manifest.json`. Extend `PREFERENCES.md` frontmatter with `sf_template_state` and `sf_template_hash`. Existing `agentic-docs-scaffold.ts` callsites unchanged externally. |
| **B** | Implement `detectScaffoldDrift`, `migrateLegacyScaffold`, and the initial `SCAFFOLD_VERSION_ARCHIVE` (empty). |
| **C** | **Automatic synchronous sync**: extend `ensureAgenticDocsScaffold` to apply `missing` + `upgradable` + legacy-migrated items in the same pass. No new command surface required for this; the existing callsites get the upgrade behaviour for free. `checkScaffoldFreshness` doctor finding for visibility. |
| **D** | **Automatic asynchronous sync via existing infrastructure**: after milestone completion (`auto-post-unit.ts`, `auto.ts:stopAuto`), dispatch a `scaffold-keeper` subagent (via the existing `subagent` extension) that runs the **`records-keeper`** skill against drifted docs. Code-as-fact verification: agent reads source and re-derives content. Surfaces results as `kind: "approval_request"` notifications using the structured-notification model from ADR-019/020. |
| **E** *(escape hatch)* | `/sf scaffold sync` command for dry-run inspection, forced refresh, and scoped operations (`--only=<glob>`, `--include-editing`). |

Each phase is independently shippable and testable. Phase A alone unlocks
the architectural property: SF can tell *pending* from *completed* on every
project from now on. Phase C is what the user experiences as "automatic"
for the simple cases; Phase D is what makes records-keeper autonomous for
the code-derived cases.

## Consequences

### Becomes possible

- Continuous template evolution: SF can iterate scaffold content freely
  knowing pending docs auto-upgrade.
- Visible signal for project staleness via doctor.
- Clean separation of *SF-managed* vs *user-owned* content per file, not per
  directory.
- Foundation for background-agent merges of customised docs.
- Future templates (new harness specs, new ADR types) propagate without
  manual project-by-project edits.

### Becomes harder

- Scaffold manager grows from "skip-if-exists" to a state machine. Test
  matrix grows accordingly.
- Every template change must consider whether to bump the SF version archive
  entry for the previous body. Forgotten archive entries cause legacy files
  to be classified `customized` when they should be `pending`.
- Marker format becomes load-bearing: changing it is itself a versioning
  problem (handled by versioning the marker schema in `schemaVersion`).

### Failure modes

| Failure | Behaviour |
|---------|-----------|
| Corrupt `scaffold-manifest.json` | Rebuilt by re-walking files; markers are source of truth. |
| Marker hash mismatch with stamped content (e.g. user hand-edited the marker) | File classified `editing`. SF will not overwrite. User can fix by running sync with `--include-editing` after reviewing the proposed file. |
| `SCAFFOLD_VERSION_ARCHIVE` missing an entry for a real prior version | Affected files classified `customized` and left alone. Recoverable by adding the archive entry in a later SF release; sync will then promote on next run. |
| Read-only filesystem | Each writer is wrapped in try/catch (same pattern as `upgradePreferencesFileIfDrifted`). Sync degrades to dry-run output. |
| Concurrent sync runs | First writer wins; second sees no drift on second pass. Manifest writes are atomic via temp+rename. |

## Alternatives Considered

| Alternative | Why rejected |
|-------------|--------------|
| Status quo (skip-and-create only) | No visibility, no refresh path, anonymous templates. The whole point of this ADR. |
| Aggressive refresh on every run (overwrite all scaffold files) | Destroys user customisations. Non-starter. |
| Git-based detection (compare repo HEAD against SF init commit) | Requires clean git state at sync time, breaks under merges/rebases, conflates user commits with SF state, fragile across worktrees (per ADR-001). |
| Per-file `.<file>.sf-meta` sidecar instead of inline marker | Doubles file count, easy to delete, harder to cite in human review. Marker travels with the file it describes. |
| Single global `SF_VERSION` stamp on the manifest only | Cannot distinguish pending vs editing per file; a single global re-stamp would either skip everything (current behaviour) or overwrite everything (rejected). Per-file state is the minimum useful granularity. |
| LLM-based "is this still pending?" classifier | Non-deterministic, expensive, unnecessary. Hash equality is the right primitive. |

## Migration

See [#7](#7-migration-strategy-for-existing-projects). One-shot, idempotent,
non-destructive. No project action required; first sync after upgrade
classifies everything correctly.

## Validation

```bash
# Once Phase A lands:
node --experimental-strip-types --test \
  src/resources/extensions/sf/tests/scaffold-versioning.test.ts

# Once Phase C lands:
sf scaffold sync --dry-run
# Expected output: structured drift report with bucket counts.
```

## References

- ADR-001 — Branchless Worktree Architecture (`.sf/` durable vs runtime
  boundary; informs which files are SF-managed vs user-curated).
- ADR-018 — Repo-native Harness Evolution (template kits and harness
  contracts that this versioning system will manage).
- ADR-019 — Workspace VM Convergence (informs where scaffold sync runs in
  the execution layer).
- `src/resources/extensions/sf/preferences-template-upgrade.ts` — prior art
  for frontmatter drift detection and silent re-stamping; the pattern this
  ADR generalises to all scaffold-managed files.
- `src/resources/extensions/sf/agentic-docs-scaffold.ts` — current scaffold
  list and skip-if-exists logic, to be extended in Phase A.
- `src/resources/extensions/sf/doc-checker.ts` — existing scaffold-content
  checker, sibling to the new freshness check in Phase C.
